Background: Physical and cognitive function decline with age. Slow walking speed has been associated with negative health outcomes and dementia is often preceded by cognitive decline. This study investigated walking speed, cognitive function and the interaction between changes in these measures in relation to dementia risk.
Method: Walking speed and cognition were assessed in 3,932 individuals aged ≥60 years at wave 1 (2002-03) and 2 (2004-05) of the English Longitudinal Study of Ageing. New dementia cases were assessed from wave 3 (2006-07) to wave 7 (2014-15). The associations were modelled using Cox proportional hazards regression.
Results: Participants with faster baseline walking speeds (HR 0.36; 95% CI 0.22 - 0.60) had a decreased risk of dementia. Those who had a greater decline in walking speed (waves 1 - 2 (HR 1.23; 95% CI 1.03 - 1.47) had an increased dementia risk. Participants with greater baseline cognition (HR 0.42; 95% CI 0.34 - 0.54) had a reduced dementia risk. Those who had a greater decline in cognition (waves 1-2) had a greater risk of dementia (HR 1.78; 95% CI 36 1.53 - 2.06). Change in walking speed and change in cognition did not interact significantly in relation to dementia risk (HR 1.01; 95% CI 0.88 – 1.17).
Conclusions: In this community-dwelling sample of English adults those with slower walking speeds and a greater decline in speed over time had an increased risk of developing dementia independent of changes in cognition. Further research is required to understand the mechanisms that may drive these associations
